1. Field of the Invention
The present invention relates to a control system for a magnetic disk drive system and, more particularly, to an improved method to control movement of a read/write transducer associated with a magnetic disk drive system.
2. Description of the Prior Art
In the field of electronic data handling, it is conventional to store data in binary form on the face of a rotatable disk. In operation, such a disk is rotated by a so-called spindle motor and the binary data is encoded upon, or retrieved from, the face of the disk by a movable electromagnetic transducer device often referred to as a read/write head. More particularly, the binary information is magnetically encoded on the face of the disk in concentric rings, called tracks, and the read/write transducer is selectively positioned by a pivoted read/write arm to move across the face of the disk in order to locate a particular track at which information is to be recorded or retrieved. Once a desired track is located, rotation of the magnetic disk will bring the read/write transducer to a particular location on the track, called a sector location, at which the read or write operation will be accomplished. A typical five and one-quarter inch diameter disk, for example, has four hundred to six hundred tracks for data storage and thirty-two sectors per track.
In many magnetic recording disk systems, the read/write transducer is driven to seek a desired track on the disk by means of a motor called a stepper motor coupled to a capstan mechanism. Such motors and capstan mechanism translate electrical commands from a controller for the disk drive system to discrete mechanical steps of the read/write transducer across the face of the magnetic recording disk. In such systems, to accurately locate the read/write transducer at a particular location on a desired track on a magnetic disk, it is necessary that the controller receive certain orientation information. Accordingly, in a typical closed-loop servo system, the controller will cause the read/write arm to move such that the read/write transducer is placed at a track which is calculated to be the desired track; then, once the read/write transducer is on that track, the transducer will read information from the track to verify that the location is, in fact, the desired one.